Silvana P. Durante

Nesting ecology of Megachile (Chrysosarus) catamarcensis Schrottky (Hymenoptera: Megachilidae), a Prosopis-specialist bee

Summary Nests of the leafcutting bee Megachile (Chrysosarus) catamarcensis Schrottky (Hymenoptera: Megachilidae) were obtained during a 24 month trap-nesting programme in a xeric forest in the Province of La Pampa, Argentina. Nests were constructed in December and January; females made an average of 4.0 ± 2.2 cells, and used mud with flower petals and/or leaf pieces to build their nests. Provisions of cells were practically pure pollen mass of Proposis caldenia. Adult emergence showed a unimodal pattern, suggesting a univoltine life cycle. However, two individuals that emerged a month after the traps were collected indicate the existence of a small early-summer generation. This could indicate that M. catamarcensis, in some years (warmer) or in some populations (at lower latitudes), could exhibit a bivoltine life cycle. Approximately 15.3 % of all offspring failed to complete development to the adult stage, and an additional 13.9 % were killed by natural enemies. These included diverse parasitic wasps (Chrysididae, Sapygidae, and Leucospidae), a cleptoparasite bee (Megachilidae: Coelioxys), and a bee fly (Bombyliidae: Antrhax).

Occurrence of the exotic leafcutter bee Megachile (Eutricharaea) concinna (Hymenoptera: Megachilidae) in southern South America. An accidental introduction?

Summary Here we report for the first time the presence of the exotic leafcutter bee Megachile (Eutricharaea) concinna in South America, based on specimens collected in the northeast part of Buenos Aires province, Argentina. We believe that M. concinna accidentally entered the country probably together with the introduction of M. rotundata to different regions of the country for commercial purposes since the 1970s. A diagnosis, illustrations, flowers records, and nesting data are given.

Comparative Morphology of Mouthparts in Species of the Genus Acalymma Barber (Coleoptera, Chrysomelidae, Galerucinae)

Abstract The genus Acalymma Barber comprises 72 species widely distributed in America, mainly in the neotropical region. The taxonomy of this genus is in a confused state because of the superficial similarity of all species, which posses similar color patterns and elytral punctation. The significance of mouthpart characters for assessing phylogenetic relationships among subfamilies of Chrysomelidae, and especially the Alticinae and Galerucinae, has been noted by various authors. The present paper is a comparative morphological study of mouthparts based on 14 species of Acalymma. As a result of this study, the taxonomic value of the mouthparts for recognizing species is established.

Description of the male, new geographical record, and biological notes on the small resin bee Hypanthidioides (Ctenanthidium) bifasciata (Urban, 1993) (Hymenoptera: Megachilidae)

Abstract. We describe and figure the previously unknown male of Hypanthidioides (Ctenanthidium) bifasciata (Urban, 1993) based on specimens reared from a trap nest along with a female. This species, originally known only from the type specimen collected in Colonia, Uruguay, is also newly recorded from Buenos Aires, Argentina. We provide for the first time information on the nest structure and, based on the analysis of pollen grains from brood cells, record five host plant species belonging to the families Apiaceae, Asteraceae, Brassicaceae, and Fabaceae. Most pollen grains belong to an undetermined species of the genus Melilotus L. (Fabaceae).

First description of male of Megachile (Pseudocentron) gomphrenoides Vachal and redescription of female (Hymenoptera, Megachilidae)

ABSTRACT Megachile is one of the largest genus of the family Megachilidae widely distributed in temperate and tropical areas of the world. Megachile (Pseudocentron) gomphrenoides was described by Vachal (1908) based on three female collected in Buenos Aires. Recently in a work about nest building of bees, we obtained females and males of this species in trap-nest. In this paper, the original description of the female is enlarged and the first description of the male is provided. Additionally, floral host and new record geographical are presented.

Redescription of Chaetochile as Subgenus of Megachile (Hymenoptera, Megachilidae)

Abstract Chaetochile Mitchell (Megachilidae) is herein confirmed as a subgenus of Megachile and represented by one species M. (Chaetochile) mitchelli Raw. The subgenus is characterized by a clypeus and supraclypeal area which is flat in the female, a second mandibular tooth which truncate and closer to the first than to the third tooth; T6 with an anterior depression and the distal margin with a conspicuous expansion and one spine on each side in the male. This contribution includes a redescription of M. Chaetochile and its single species.

El subgénero Megachile (Dasymegachile) Mitchell con especial referencia a las especies argentinas (Hymenoptera: Megachilidae)

Seventeen species of Megachile (Dasymegachile) are recognized, twelve species from Chile, nine species from Argentina, three from Peru and one from Bolivia. Descriptions, illustrations, and keys for the identification for the Argentinean species are provided. The geographical distributions in Argentina are revised; M. cinerea and M. melanotricha are recorded for the first time from Argentina. Two species are also newly recorded from Chile.

Descriptions of unknown sexes, new geographical records, and host associations for two South American species of Megachile (Hymenoptera: Megachilidae)

The cosmopolitan genus Megachile include many species described on the basis of only one sex. Sexual dimorphism is very pronounced in these taxa and therefore sexes are often difficult to associate, thus making species identification nearly impossible. The females of M. (Chrysosarus) concava and M. (Pseudocentron) variplantis are described and illustrated. Additional geographical and host records are provided as well as comments on their diagnostic features and identification based on existing keys.